This invention relates to a passenger lift system for mobile vehicular use such as in commercial buses and vans in which the lift system functions either as a retractable step system or a vertically movable platform for non-ambulatory passengers. The lift system includes a vertical safety barrier at the outermost edge of the platform which, when not in use, collapses to form the lowermost step in the step system. The lift is moved by hydraulically actuated motors or electro-mechanical devices or the like, whose operation is dependent upon the vehicle's propulsion system and is controlled appropriate electrical sensors which detect and correct any malfunction.